ATLANTA (Reuters) - More than eight million adults in the United States considered suicide in a year's time and more than two million made plans to kill themselves, according to the findings of a government study.

The study, released by the Centers for Disease Control and Prevention (CDC) showed that women, Caucasians and people under age 30 were more likely to contemplate suicide.

It also revealed a wide variation in suicidal behavior among U.S. states. One in 15 adults in Utah had serious thoughts of suicide, the highest in the nation, compared to Georgia, which had the lowest with one in 50 adults.

More than one million adults reported attempting suicide, according to the research, which included data from 2008 to 2009. Rhode Island had the highest number of reported attempts with one in 67 adults.

"We are trying to find out where the most vulnerable populations are," said Dr. Alex E. Crosby, a CDC epidemiologist and one of the authors of the study.

Each year, about 35,000 adults in the United States commit suicide, Crosby said. Although the study did not examine the causes of the variations by state, possible factors are differences in demographics and access to health care.

"One state may have a higher population that is young and female," he said.

The large variation requires having more than one strategy for fighting suicide, the CDC said.

"We need to work together to raise awareness about suicide and learn more about interventions that work to prevent this public health problem," Dr. Thomas Frieden, director of the CDC, said in a statement.